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Eyeshine videos.zip: Raw AVIvideo recordings taken using a custom-built ophthalmoscope to assess differences in luminous pseudopupil physiology between four ithomiine butterfly species after dark adaptation. Filename key: "_30sec": 30 seconds of dark adaptation, "_1min": 1 minuteof dark adaptation, "_5min": 5 minutes of dark adaptation, "_10min": 10 minutes of dark adaptation, "_20min": 20 minutesof dark adaptation, "_dorsal": dorsal eye region (10 minutes of dark adaptation), "_ventral": ventral eye region (10 minutes of dark adaptation) Substacked microCT scans.zip: TIFs of substacked micro-computed tomogrpahy (microCT) scans for all ithomiine individuals. For details, see methods in Wainwrightet al.(2023)

For many animals, the availability and provision of dietary resources can vary markedly between juvenile and adult stages, often leading to a temporal separation of nutrient acquisition and use. Juvenile developmental programs are likely limited by the energetic demands of many adult tissues and processes with early developmental origins. Enhanced dietary quality in the adult stage may, therefore, alter selection on life history and growth patterns in juvenile stages. Heliconius are unique among butterflies in actively collecting and digesting pollen grains, which provide an adult source of essential amino acids. The origin of pollen feeding has therefore previously been hypothesized to lift constraints on larval growth rates, allowing Heliconius to spend less time as larvae when they are most vulnerable to predation. By measuring larval and pupal life-history traits across three pollen-feeding and three nonpollen-feeding Heliconiini, we provide the first test of this hypothesis. Although we detect significant interspecific variation in larval and pupal development, we do not find any consistent shift associated with pollen feeding. We discuss how this result may fit with patterns of nitrogen allocation, the benefits of nitrogenous stores, and developmental limitations on growth. Our results provide a framework for studies aiming to link innovations in adult Heliconius to altered selection regimes and developmental programs in early life stages.

Grid of 24 artificial flowers composed of 12 purple (rewarding) and 12 yellow flowers (unrewarding) with randomised positions. a. Illustration of the grid. b. Experimental butterflies exploring the grid of flowers. ;Scheme for selecting demonstrators. During training, butterflies were split into two groups (control and knowledgeable) and trained with a grid of rewarding artificial flowers. For the first group, either purple or yellow flowers were rewarding. For the other, only purple flowers were rewarding. To check for final preference, butterflies were tested individually with unrewarding artificial flowers. ;Scheme for the social knowledgeable approach. During pre-training, observers from both groups were kept together. During trialling, butterflies were split into two groups (control and knowledgeable) with a pair of observers exploring the grid of flowers along with 10 demonstrators.;Preference for purple colour for H. erato observers assigned either to control or knowledgeable groups on the first day of the social learning experiment. Flowers used in the naive preference test were devoid of rewards. Squares and whiskers are means of individuals’ preference ± 95% CI. ;Preference for rewarding colour as a function of trial day in H. erato observers during the social learning experiment. Points are individual observations. Squares and whiskers are means of individuals’ preference ± 95% CI. **p < 0.01.

Supplementary tables and figures

Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae, and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. By contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, coloration and social behaviour covary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey.